Nitric Acid → Methyl-4-nitropyrrole-2-carboxylic acid
Reaction equation
[N+:1]([O-:4])(O)=[O:2].C[N:6]1[CH:10]=[CH:9][CH:8]=[C:7]1[C:11]([OH:13])=[O:12].[CH3:14]C(OC(C)=O)=O>>[CH3:14][C:8]1[C:9]([N+:1]([O-:4])=[O:2])=[CH:10][NH:6][C:7]=1[C:11]([OH:13])=[O:12]Participants
4
Procedure
Acetic anhydride (8 ml) and nitric acid (70%, 1.6 mL) were heated to 50° C. for 15 minutes and cooled to room temperature. The solution was then slowly added to a suspension of 1-methyl-2-pyrrolecarboxylic acid (2.0 g, 0.02 mol) in Ac2O (12 ml) cooled to −25° C. The mixture was stirred for 30 min at −15° C., warmed to room temperature and stirred for another 20 min. The mixture was again cooled to −25° C. and the resulting precipitate collected in a funnel cooled with dry ice. The solid was washed with cold Ac2O (−25° C.), followed by Ac2O:CCl4 (1:1, −25° C.), and then CCl4 and hexane. The yellow solid was dissolved in NaOH (1M) and acidified with HCl to yield the product as a light cream solid which was collected and air-dried. Yield 0.98 g (36%). 1H NMR (DMSO): δ 8.19 (d, 1H, J=1.8 Hz); 7.23 (d, 1H, J=2.0 Hz); 3.90 (s, 3H).